Traffic pollution linked to autism

27th November 2012

Researchers in California say there is a link between the incidence of autism in children and levels of traffic pollution.

In a study of more than 500 children, they found children who breathed the most polluted air were three times more likely to have autism than those who had less environmental air pollution in childhood.

The findings have already proved controversial, however, with experts saying the explanation is unconvincing as a cause for autism spectrum disorders, which can cause difficulties with communication and social skills.

Those on the spectrum face isolation and emotional problems, although the extent to which people are affected varies widely.

Some live full and functioning lives, while others need constant support and are unable to take part in mainstream society.

More than 580,000 people are believed to be on the spectrum in the UK alone.

For the purposes of the study, the researchers compiled data on levels of air pollution at various addresses in California, and used it to compare exposure to pollution in the womb and in the first year of life.

They studied 279 children with autism, and 245 without.

They found children in the most polluted neighbourhoods were three times more likely to have an autism diagnosis than those who lived in the cleanest environments.

The same research team has previously shown a link between autism and living close to major roads.

They say that air pollution could have lasting neurological effects, but other researchers have questioned how air pollution could affect brain development.

The study failed to delineate a convincing mechanism whereby pollutants could affect the developing brain, resulting in autism, according to Uta Frith, cognitive development professor at University College, London.

Other factors affecting the probability of developing autism, such as a person's genes, were not taken into account by the study.

However, the study stopped short of saying that autism is caused by traffic pollution.

However, Cambridge University autism researcher Sophia Xiang Sun said air pollution contributes to many other diseases and conditions, so it is biologically plausible that it could have a role in the pathways of autism.